Thunder Lecture III

1. Thunder Lecture III

2. Shanghai Institute for Advanced Studies Fudan University 04.04.2006 Nano-Bionik Micro- and Nanotechnology in Nature Ingo Rechenberg

3. Bionics Biomimicry Biomimetics What is Bionik ? The study of the results of biological evolution from the engineering point of view from the engineering point of view Learning from nature‘s way of engineering

4. Bacteria flagellum Micro&nano-structured biological surfaces Biological selfassembly Protein machines Biological receptors Muscle filaments Nano-Bionik

5. The topics The Lotus-Flower-Effect: Self-cleaning property through hydrophobic micro-dots. The Moth-Eye-Effect: The art to be invisible through optical nano-burls. The Gecko-Foot-Effect:Sticking on the wall through elastic nano-hairs. The Sand-Skink-Effect:Reduction of friction and wear through nano-thresholds. The Darkling-Beetle-Effect:Collecting dew through hydrophilic/hydrophobic micro-spots. The Shark-Scale-Effect:Turbulence reduction through longitudinal micro-grooves. The Water Strider-Effect: To keep dry through micro-hairs with nano-ridges.

6. Nano-spikes Nano-thresholds Nano-grooves Nano-humps Nano-burls Nano-bumps Nano-ladders Nano-ribs Nano-knobs Nano-patterns in nature ? ?

7. The sacred Lotus flower is a symbol of purity in Asian religions. The Lotus-Flower-Effect

8. Honey rolls down from a “Lotus-Effect-spoon” The Lotus-Effect® Water droplets roll down the leaf of the Lotus flower Glue rolls down the leaf of the Lotus flower A droplet takes up the dirt while rolling down

9. 30μm Microrelief of the leave The development of the Lotus-Effect® paint Bionik-product Self cleaning

10. Lotusan facade paint Standard facade paint Test areas at the wall of my house after 4 years

11. Adhesion > Cohesion Adhesion < Cohesion Surface tension and wetting angle Adhesion << Cohesion

12. smooth surface Lotus-Effect® surface The Lotus-Effect in action

13. Lotus-Effect® roof tile Lotus-Effect® tie Prof. Wilhelm Barthlott

14. 1×1 cm engineering imitation Secondary structure Lotus leaf The Lotus-Effect extended

15. Water droplet Water droplet The Lotus-Effect extended

16. The Moth-Eye-Effect

17. 130 x 420 x 1050 x 4120 x Micro-burls 100nmØ Micro-optics of the moth eye

18. < l light Air Optical transparent layer Reflection of the light is avoided by a continuously increasing refractive index of the optical medium Glass Deception of the light The little burls on the surface of the optical medium work as a gentle increase of the refractive index

19. All the light is captured by th eye Moonlight is not mirrored (predatory!) Night-flying insect

20. Invisible Jelly Fish

21. Technological imitation of the nanostructure of a moth eye. Periodicity of the burls: 300 nm. Glass pane with Moth-Eye-Effect

22. The Moth-Eye-Effect

23. The wonder of the Gecko toes

24. 500000000 nanohairs 2 kg (theoretically) Photo: M. Moffet Geckos get a grip using Van-der-Waals-forces Gecko sticking at the wall

25. The seta has 1000 nanohairs The Gecko toe has 500000 microhairs (setae) Nanostructure of the Gecko toe

26. Adhesion effect through Van-der-Waals-forces The Gecko effect Technical surface 1 Contact area Technical surface Technical surface 2 Nanohairs ! Large contact area large adhesion force Small contact area small adhesion force Microhair

27. Synthetic Gecko hairs necessary for spider man (New Scientist 15. 05. 2003)

28. Gecko-Tape

29. ? The Sandfish lives in the Sahara desert The Sandfish-Effect

30. Sandfish ? Fishing rod

31. 0 s The Sandfish ¼ s ½ s dives down

32. Characteristics of the sandfish scales M. Zwanzig, IZM Friction Abrasion sand flow Electron emission 8µm

33. My Sahara Lab Field work in the Sahara GPS: N 31°-15‘–02“ W 03°-59‘–13“ Erg Chebbi

34. Simple apparatus to measure the dynamic friction coefficient of flowing sand Sand tubule Angular scale Object platform Hand lever

35. Measurement of the dynamic friction coefficient

36. 20° Sand flow is moving 18° Sand flow stops Sandskink Measurement of the angle of sliding friction

37. 0 40 0 35 0 30 sliding angle 0 25 n 0 20 o n d l f o n ss e l 0 a y T 15 a S N l teel k G n 0 10 i S k S Sahara-Measurement 2002 0 5 0 0 Sliding friction: Sandfish versus engineering materials

38. Friction measurements with a sand-filled cylinder

39. 58 % Sand-cylinder measurements 2003 Steel = 19° Sliding angle: Sandskink = 12° Caudal Sandskink = 18° Cranial

40. 50nmØ Sandfish scale under the electron mikroscop (REM) scale Sand sflow 8µm at the back at th belly

41. Sand flow 6µm Oblique view of the nano-thresholds

42. Sliding direction Size comparison Grain of sand upon the thresholds

43. Abrasion of the sandfish scales

44. The sandskink always looks shiny while Man-made things soon get blunt in the desert wind ! The resistance to abrasion

45. Simple apparatus for the abrasion tests Sandfunnel Sandblast Objectplatform

46. Impact point of the sandblast Impact time: 10 hours ! Steel Abrasive spot: Glass

47. Glass Magnification ≈200 Sand abrasion under the microscope 2 hours impact time 20 cm blast height Scotch tape protected Sand blast Sandfish Magnification ≈1000 Sandfish Magnification ≈1000 Afterward Before

48. Kenyan Sandboa Sandskink Parallel Evolution

49. Sandskink Kenyan Sandboa Sandskink Parallel Evolution

50. Aporosaura anchita Sand-diving lizard in the Namib desert Namib